1. Field of the Invention
This invention relates to micromachined fluid handling structures and more specifically to an easily assembled housing for such a structure.
2. Description of the Prior Art
Micromachined fluid (gas and/or liquid) handling structures are well known. For examples see U.S. Pat. No. 4,471,647 to Jerman et al. and U.S. Pat. No. 4,474,889 to Terry et al., incorporated herein by reference in their entirety, describing respectively a micromachined detector and a fluid valve assembly. These structures (e.g. manifolds, fluid flow and pressure sensors, etc.) include channels and valves which are micromachined by semiconductor-type fabrication techniques typically involving forming structures by photolithography of silicon wafers. The micromachined structure is usually a laminate of several such micromachined layers (including sometimes Pyrex layers or other materials) which are bonded together. In the prior art these micromachined fluid handling structures connect to external components and systems via stainless steel tubes which are permanently bonded to the micromachined structure. The micromachined structure is then permanently encapsulated into a protective body, typically plastic or elastomer. Thus in the prior art this entire assembly is permanently fastened together.
It is not unusual for the micromachined structure to fail, e.g. due to clogs. In this case, the entire assembly is disposed of and replaced with a new one. This is of course expensive. Moreover, not only is the micromachined structure disposed of, also of necessity the connecting tubes which are permanently bonded to the micromachined structure are also thrown away. Therefore replacement of this assembly, in for instance a gas chromatograph instrument, requires factory repair.
Also, initial assembly of such devices in the factory environment is complex, requiring careful alignment and use of suitable adhesives. An additional problem is that many common adhesives are not adequate for high temperature applications.
Thus there is a need for an improved micromachined fluid handling assembly and especially for one which is relatively easy to manufacture and is field replaceable.